1. Field of the Invention
The present invention relates to an automatic pin inserting apparatus for inserting a pin into a frame shaped workpiece. More specifically, the invention can be utilized for frame-shaped workpieces having a welded structure.
2. Description of Related Art
FIGS. 7, 8 and 9 illustrate a frame-shaped workpiece W of a welded structure, having tapered pin P inserted in pin-hole H which is located therein. When inserting pin P, it is difficult to detect the exact location of pin-hole H correctly, because an insertion allowance between the leading end outside diameter d of the tapered pin P and the inside diameter D of the pin-hole H is relatively small. In addition, the location of the pin-hole H can vary randomly, due to typical tolerances associated with a welded construction.
Therefore, the conventional method of alignment and the insertion of the tapered pin P with the pin-hole H is to use a manual operation.
For example, assume the inside diameter D of the pin-hole H is 3.1 mm, the leading end outside diameter d of the tapered pin P is 2.9 mm, and the variation of the pin-hole location is .+-.1.0 mm max. In this case, an insertion allowance is calculated as 3.1-2.9=0.2. The fact that a value of insertion allowance is 0.2 means that a value of tolerance in directions of X and Y, respectively, is .+-.0.1 mm This tolerance (.+-.0.1 mm) is considered extraordinarily small.
An apparatus being capable of detecting a location of a pin-hole with such a small tolerance and inserting a pin automatically into the pin-hole does not presently exist.